OLED Pixel Circuit Pre-Charging Parasitic Capacitance

The patent applies preliminary action by pre-charging the parasitic capacitance of the OLED during the sampling period before the emission period. This is achieved by controlling the switch elements to connect the data voltage to the OLED anode through the driving element during sampling, thereby charging the parasitic capacitance in advance. During the subsequent emission period, the pre-charged parasitic capacitance maintains stable voltage, improving low gradation expression characteristics without compromising OLED efficiency.

The patent eliminates flicker in low speed driving mode by pre-charging the parasitic capacitance during the sampling period before emission. The switch elements are controlled to maintain a stable voltage across the OLED anode by charging the parasitic capacitance in advance, ensuring continuous stable operation during emission even at low driving speeds, thereby preventing flicker while maintaining high OLED efficiency.

The patent resolves the time delay in parasitic capacitance charging by performing the charging action preliminarily during the sampling period at higher current, before the emission period begins. During sampling, switch elements are controlled to allow sufficient current to charge the parasitic capacitance completely. During the subsequent emission period, the pre-charged capacitance maintains voltage stability even at low current, thereby eliminating charging delay during low gradation emission while still achieving low energy consumption.

The patent achieves electrical characteristic compensation without increasing device complexity by making the existing pixel circuit components perform multiple functions. The switch elements (first, second, third, fourth switches) control multiple operations including data writing, threshold voltage sampling, and parasitic capacitance pre-charging. The capacitors (first, second, third capacitors) serve dual purposes of storing threshold voltage and pre-charging parasitic capacitance. This multi-functional design provides compensation capability while avoiding additional dedicated compensation circuits.